Make necessary change to make things work with photon 2.0 docker image.
Remove distro-sync to mitigate the build issue and add `--pull` to docker build
command to make sure the latest photon:2.0 will be pulled during build process.
Signed-off-by: Daniel Jiang <jiangd@vmware.com>
The following are done to avoid travis-ci failing due to too much log
size.
1) Update Makefile and scripts to make go build less verbose.
2) Make tdnf less verbose
